Wind turbine towers both for onshore and offshore applications are usually formed by a number of tubular tower sections. The tower sections are adapted to house a number of operating components of the wind turbine. Examples of wind turbine operating components are electrical power modules, transformer, frequency converter, switch cabinets, inverters, control units, power cables, etc.
Two main problems are associated with tower sections housing operating components.
One problem is the poor accessibility to the components inside the tower sections. Installing equipment inside the tower sections requires hoisting large and heavy operating components at large heights and fitting them inside the tower section. Once the operating components are hoisted at the desired height, they are fitted inside the tower section through openings or doors. Ladders and elevators are used for accessing the inside of the tower section. The equipment is then placed on corresponding platforms that are attached to the inner walls of the tower section. This operation is complex and time consuming due to the limited size of the openings or doors for accessing the inside of the tower section.
Another problem associated with tower sections housing operating components therein is that of safety. It is currently recommended to reduce the presence of operators as much as possible inside a wind turbine tower for installing equipment therein. This is important in order to reduce the risk of falling and other potential dangers that may arise when working inside the tower, especially when working at large heights.
In this respect, alternative ways for installing operating components inside a wind turbine tower have been proposed. For example, according to document EP1788242 at least one platform is placed inside a tower section. The platform is installed from above the tower section. The platform is attached to the inner walls of the tower section. At least one operating component is then disposed on the platform. In one specific embodiment disclosed in this document, multiple groups of supporting elements are provided at the inner side of the tower section for supporting a number of corresponding platforms. The groups of supporting elements are arranged offset with respect to each other in a circumferential direction at different heights. Therefore, when viewed along the longitudinal axis of the tower section, the supporting elements of the individual groups of supporting elements do not overlap each other. Each platform, after being aligned with the supporting elements of the associated group of supporting elements, can be lowered into the tower section without interfering with the supporting element of the respective other groups of supporting elements.
Attaching supporting elements to the tower section offset with respect to each other in a circumferential direction at different points results in a complex and time consuming manufacturing process. Errors in positioning of welding for attachment of the supporting elements may occur and therefore problems in assembling of the platforms inside the tower section.